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Fracture resistance of CAD/CAM-milled, 3D-printed, and customized fiber post-and-core systems: an in vitro study
Hoda Alaa El-Din Selim El-Shorbagy1,2, Ghada A E Hussien3, Hoda M Abel Sadek3
1Fixed prosthodontics department, Faculty of Dentistry, Ain Shams University, El-Khalyfa El-Mamoun Street Abbasya, Cairo, Egypt. Hoda.elshorbagy@gu.edu.eg.
Background:
Post-and-core systems are frequently used when restoring endodontically treated teeth. CAD/CAM technologies contribute to post fabrication by improving material uniformity and adaptation to canal morphology. Additionally, 3D printing presents an emerging approach that constructs posts incrementally and may address certain limitations associated with traditional fabrication methods. The purpose of this in vitro study was to evaluate the fracture resistance of custom-made CAD/CAM posts and cores fabricated using milling and additive techniques compared to customized fiber posts.
Materials And Methods:
Twenty-one maxillary central incisors were randomly divided into three groups (n = 7): Group MP (milled posts), Group 3D (3D printed posts), and Group CF (customized fiber posts). The teeth were embedded in acrylic resin and prepared endodontically. Post spaces were created using standardized drills. For Groups MP and 3D, the post spaces were scanned, and posts were fabricated using CAD/CAM technology and 3D printing. In Group CF, posts were customized with resin composite. All posts were cemented with resin cement. The specimens were subjected to thermocycling for 5,000 cycles. Fracture resistance was measured using a universal testing machine, and failure modes were examined with a stereomicroscope. The Kruskal-Wallis test was used to compare the three groups. Failure mode data were reported as frequencies and percentages. Fisher's Exact test was used to compare failure modes among the three groups.
Results:
There was no statistically significant difference in fracture resistance among the three groups (p = 0.400) or in failure modes (p = 0.381). The 3D group exhibited the highest percentage of restorable failures (85.7%), while the Milled group showed the highest percentage of non-restorable failures (57.1%).
Conclusions:
All post types demonstrated comparable fracture resistance and favorable failure modes when restoring anterior endodontically treated teeth. Milled composite blocks and 3D-printable materials effectively produced one-piece post-and-core structures using CAD/CAM technology with fracture resistance falling within the typical masticatory forces for maxillary anterior teeth.
